This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Use of Electrical Impedence to Measure Lean Body Weight as a Determinant of the Dose of Contrast Media for Abdominal CT (NCT02170688), a randomized phase 4 study. The primary outcome is Difference in Enhancement of the Liver and Blood Vessels Over Time, Measured in Hounsfield Units (HU).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02170688 |
| Phase | Phase 4 |
| Condition | IV Contrast Dosing |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 139 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Duke University |
| Results posted | Yes |
2. Clinical Question
Population
People undergoing abdominal CT with intravenous contrast. The registry record reports total enrollment of 139, but does not describe the enrolled population in further detail.
Intervention
Contrast volume determined by total body weight, calculated lean body weight, measured lean body weight, or estimated lean body weight. The measured approach uses a body composition analyzer; the estimated approach uses a software program and digital scout radiograph measurements.
Comparator
A fixed contrast dose, described as 125 mL of Isovue 370, administered at 4 mL/sec. The record identifies this as the standard procedure at Duke.
Primary question
How do the dosing approaches compare in the difference in liver and blood-vessel enhancement, measured in Hounsfield units, from baseline to post-dose imaging approximately 1hr after contrast administration?
The study addresses a practical measurement and dosing question: whether contrast volume can be set using measures of body size other than a fixed amount. The registry description names five approaches: fixed dose, total body weight, calculated lean body weight, measured lean body weight, and estimated lean body weight. The comparison is therefore broader than a single contrast between fixed dosing and weight-based dosing.
The registry record identifies the primary endpoint as the difference in enhancement over time. It also lists contrast volume used as a secondary outcome. No numerical endpoint results or analysis comparing the approaches are reported in the registry record, so the relative enhancement or contrast-volume findings cannot be described from this record.
3. Trial Design
This is a Phase 4, randomized, single-masked, parallel-group trial sponsored by Duke University. The registry record lists the condition as IV Contrast Dosing and the intervention as Isovue 370 and weight calculation. It gives total enrollment as 139 and status as completed. The recorded study start is 2004-02, and primary completion is recorded as 2014-07.
The study description sets out five methods for determining contrast volume. The fixed-dose group is described as receiving 125 mL of Isovue 370 at 4 mL/sec. The other approaches base dosing on total body weight, calculated lean body weight, measured lean body weight, or estimated lean body weight. Measured lean body weight is assessed using Tanita body composition/analyzer scales. Estimated lean body weight is described as derived using software that measures posterior-to-anterior attenuation from a digital scout radiograph. Some arm descriptions are incomplete in the registry record, so the full dosing procedures for those approaches are not available there.
The arm descriptions list intended group sizes, while the registry reports overall enrollment as 139. The number of participants actually assigned to each group, the number completing the study, and any participant flow by arm are not reported in the registry record. The record identifies the design as randomized and parallel but does not report the randomization procedure, allocation concealment, or which individuals were masked.
The primary measurement is enhancement in liver and blood-vessel regions, assessed before contrast and on post-contrast images. The endpoint description refers to liver parenchyma, the portal vein, and the abdominal aorta, with their measurements combined as a summed measurement. Contrast volume used is listed as a secondary outcome. No statistical analyses are registered in the posted results.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Fixed Dose | Total Body Weight | Calculated Lean Body Weight | Measured Lean Body Weight | Estimated Lean Body (eLBW) Weight |
|---|---|---|---|---|---|
| STARTED | 29 | 29 | 29 | 27 | 25 |
| COMPLETED | 25 | 26 | 25 | 25 | 25 |
| NOT COMPLETED | 4 | 3 | 4 | 2 | 0 |
Reasons for not completing this period:
| Reason | Fixed Dose | Total Body Weight | Calculated Lean Body Weight | Measured Lean Body Weight | Estimated Lean Body (eLBW) Weight |
|---|---|---|---|---|---|
| Exclusion Criteria: Fatty Liver | 4 | 2 | 3 | 2 | 0 |
| Full dose not received | 0 | 1 | 0 | 0 | 0 |
| Physician Decision | 0 | 0 | 1 | 0 | 0 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Fixed Dose | Total Body Weight | Calculated Lean Body Weight | Measured Lean Body Weight | Estimated Lean Body (eLBW) Weight | Total |
|---|---|---|---|---|---|---|---|
| Participants analysed | 29 | 29 | 29 | 27 | 25 | 139 | |
| Age, Customized: ≥18 years | participants | 29 | 29 | 29 | 27 | 25 | 139 |
| Sex: Female, Male: Female | Participants | 9 | 17 | 10 | 13 | 12 | 61 |
| Sex: Female, Male: Male | Participants | 20 | 12 | 19 | 14 | 13 | 78 |
| Region of Enrollment: United States | participants | 29 | 29 | 29 | 27 | 25 | 139 |
6. Primary Endpoint
The registry lists the primary outcome as Difference in Enhancement of the Liver and Blood Vessels Over Time, Measured in Hounsfield Units (HU), measured over baseline, post-dose imaging (approximately 1hr).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Hounsfield units (HU) |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the difference in enhancement of the liver and blood vessels over time, measured in Hounsfield units (HU). Enhancement is assessed at baseline, before contrast administration, and in post-dose imaging approximately 1hr after administration. The endpoint description specifies operator-defined regions of interest in liver parenchyma, the portal vein, and the abdominal aorta. Measurements from the three areas are combined as a summed measurement.
In general, Hounsfield units express radiographic attenuation. Comparing measurements before and after contrast administration is intended to describe the change in image attenuation associated with the imaging procedure. The endpoint therefore focuses on an imaging measurement, rather than a clinical outcome such as symptoms or diagnosis. The registry lists the outcome parameter as a mean and its dispersion as a standard deviation.
The registry does not report the numerical enhancement values, standard deviations, or a treatment-group contrast for this endpoint. It also does not provide enough information to determine precisely how the summed measurement was constructed or how measurements from the post-contrast slices were incorporated into the final analysis. The endpoint's definition and measurement times are reported, but its results and analysis are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry establishes the study question and names its primary imaging outcome, but it does not provide numerical results for that outcome. The record identifies enhancement in liver and blood-vessel regions, measured in Hounsfield units, as the primary endpoint. It describes baseline and post-dose measurement, with post-dose imaging approximately 1hr after contrast administration. However, no group means, standard deviations, estimated differences, confidence intervals, or p-values for enhancement are reported in the registry record. There is consequently no posted estimate of how the five dosing approaches compare on the primary endpoint.
The registry also lists difference in volume of contrast used, measured in milliliters, as a secondary outcome. It does not report numerical results for that measure either. No conclusions about the amount of contrast used under the different methods can be drawn from the listed outcome definition alone.
The trial is described as randomized and parallel-group, which identifies the intended design for comparing dosing strategies. Randomization can support fair comparisons when assignment and follow-up are implemented and analyzed appropriately. The registry does not report the allocation procedure, participant flow by group, analysis populations, or an inferential analysis. Those details are needed to assess how the planned comparison was carried out and how much uncertainty surrounds any estimated differences.
The registry lists total enrollment as 139, but that number does not reveal how many participants contributed usable endpoint measurements in each group. The arm descriptions give group sizes, but the record does not report actual assignment or endpoint availability by arm. Thus the overall enrollment should not be treated as the analysis sample for the primary endpoint.
In general, an estimate is most informative when read together with its uncertainty. A confidence interval indicates a range of values compatible with the data and analysis assumptions; without an estimate and interval, the precision of an effect cannot be evaluated. The registry record provides neither. It also does not report a statistical model or a complete analysis plan, so there is no basis for reconstructing an adjusted or unadjusted treatment comparison.
The absence of numerical results in this registry record should not be interpreted as evidence that the approaches produced equal or different enhancement. It means the registry record does not permit those conclusions. The appropriate statistical reading is limited to the trial's stated design, measurement definitions, and outcomes, with the outcome effects and their precision not reported in the registry record.
9. Statistical Methods Explained
Statistical interpretation depends on how the trial was designed, how its measurements were summarized, and how uncertainty was quantified. The registry describes a randomized, single-masked, parallel-group design and continuous outcomes summarized using means and standard deviations. It does not report any analyses, so statistical methods beyond those elements cannot be attributed to the trial.
What does the randomized parallel design mean?
In general, random allocation assigns participants to intervention groups using a chance-based process. If performed appropriately, it helps balance both measured and unmeasured participant characteristics across groups on average. A parallel-group design means participants are assigned to a group and assessed under that group’s approach rather than crossing through all approaches. These general design features explain why group comparisons can be useful, but they do not establish how allocation was generated or concealed in this trial. Those details are not reported in the registry record.
The record labels masking as single, but does not say which parties were masked. Masking can reduce the influence of expectations on measurements or other study procedures, depending on who is unaware of group assignment. Without further detail, it is not possible to determine where masking applied or whether it could affect operator-defined regions of interest.
How should a continuous endpoint be read?
General statistical explanation: a continuous outcome can take many values along a measurement scale. A mean describes the average within a group, while a standard deviation describes the spread of individual measurements around that group mean. A difference between group means can estimate the average contrast between approaches. The difference is easier to interpret when accompanied by a confidence interval, which conveys uncertainty about the estimate under the analysis assumptions.
The registry specifies a mean and standard deviation for the primary endpoint, but gives no numerical summaries. It also does not report a confidence interval or a group comparison. Thus the endpoint's stated summary type does not itself supply evidence about the size, direction, or precision of any difference.
Why does the outcome definition matter?
The primary outcome combines enhancement measurements from liver parenchyma, the portal vein, and the abdominal aorta as a summed measurement. In general, combining measurements can produce a summary that reflects several anatomical regions, but interpretation depends on the exact calculation and on how multiple image slices are handled. The registry describes operator-defined regions and measurement across liver slices after contrast, but does not give a complete calculation rule. It also does not report whether any measurements were repeated or how differences between operators were handled.
The endpoint has baseline and post-dose time points, with post-dose imaging approximately 1hr after administration. A change-from-baseline analysis and a comparison of post-dose values adjusted for baseline are possible general approaches, but the registry does not state which was used. No particular model or estimator should be inferred from the endpoint title.
What do the planning assumptions tell readers?
The registry includes assumptions for a planning illustration based on the observed effect: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The target effect is specified as a stated fraction of the observed effect. For non-time-to-event outcomes, the illustration is expressed as participants per arm for 80% or 90% power. These are planning assumptions, not proof that the trial was designed with those targets and not an estimate of the probability that the study detected an effect. The registry does not report the trial's own sample-size justification.
In general, a planning calculation estimates the sample size needed to detect a chosen effect under specified assumptions. If the chosen effect is based on an observed estimate, the result depends on that estimate and should not be interpreted as observed power. The record's planning assumptions do not substitute for an analysis of the trial data. No numerical planning estimates or observed effect estimates are reported in the registry record.
Why can extra variability matter?
General statistical explanation: a standard deviation describes variability within groups. Greater variability makes it harder to distinguish a group difference from random variation, all else being equal. If outcome variability exceeds what a model assumes, standard errors and confidence intervals may be unreliable unless the analysis accounts for that feature. Over-dispersion is especially relevant when data are more variable than a model expects, but the registry does not report an over-dispersion assessment or indicate that a model requiring such an adjustment was used. The primary outcome is described as continuous, and the record provides no distributional diagnostics.
The central limitation for statistical interpretation is therefore not a particular method that can be critiqued, but the lack of a reported analysis. The analysis model, handling of baseline measures, approach to multiple comparisons, missing-data method, and analysis populations are not reported in the registry record. Without those details and outcome estimates, statistical significance and precision cannot be evaluated.
10. Multiplicity, Missing Data and Analysis Populations
The registry describes five dosing approaches and a primary endpoint measured across several regions and time points. It also lists contrast volume used as a secondary outcome. Multiple groups, outcome components, or comparisons can create multiplicity: when several hypotheses are tested, the chance of at least one apparently unusual result can increase. General statistical practice may address this through a prespecified primary comparison, an adjustment for multiple testing, or a clearly defined hierarchy of outcomes. The registry does not report a multiplicity strategy or identify a specific primary pairwise comparison.
The record indicates that the primary outcome has several categories or time points and is not reduced to one comparison. It reports zero registered analyses. As a result, it does not provide a reported test, model, or adjustment that can be evaluated. No inference about whether multiplicity was controlled in the trial should be made from the outcome description alone.
Missing-data information is also not reported in the registry record. It does not state how many participants had endpoint measurements, whether any measurements were incomplete, why data might be missing, or how missing observations were handled. General statistical explanation: complete-case analysis, imputation, and model-based approaches make different assumptions about missingness, so the method used can affect both estimates and uncertainty. None of these approaches can be attributed to this trial based on the record.
The analysis populations are not reported in the registry record. In particular, it does not specify whether the primary comparison included all randomized participants, only participants with available measurements, or another defined group. Actual enrollment and group-specific participant flow are also not given. These omissions prevent assessment of whether the analyzed groups followed the randomization or how missing outcomes may have influenced the results.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Fixed Dose | 0 | 25 | 0.0% |
| Total Body Weight | 0 | 26 | 0.0% |
| Calculated Lean Body Weight | 0 | 25 | 0.0% |
| Measured Lean Body Weight | 0 | 25 | 0.0% |
| Estimated Lean Body (eLBW) Weight | 0 | 25 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Fixed Dose | 0 of 25 |
| Total Body Weight | 0 of 26 |
| Calculated Lean Body Weight | 0 of 25 |
| Measured Lean Body Weight | 0 of 25 |
| Estimated Lean Body (eLBW) Weight | 0 of 25 |
The registry lists serious and other adverse-event counts for five groups. For Fixed Dose, it reports 0 serious events among 25 at risk and 0 other events among 25 at risk. For Total Body Weight, it reports 0 serious events among 26 at risk and 0 other events among 26 at risk. For Calculated Lean Body Weight, it reports 0 serious events among 25 at risk and 0 other events among 25 at risk. For Measured Lean Body Weight, it reports 0 serious events among 25 at risk and 0 other events among 25 at risk. For Estimated Lean Body (eLBW) Weight, it reports 0 serious events among 25 at risk and 0 other events among 25 at risk.
These are the event counts recorded for the listed groups; they are not a complete account of all possible safety outcomes. The registry does not report death counts, and it does not provide further information about event definitions, collection procedures, or the observation period for adverse events. The group-specific counts at risk also do not establish how many participants were analyzed for the imaging outcomes. Zero recorded events in these categories should be read as a registry count, not as proof that no adverse events of any kind occurred.
12. What the Result Does, and Does Not, Mean
The registry record describes a trial designed to compare five methods for determining contrast volume during abdominal CT. Its primary outcome focuses on enhancement measurements in the liver and blood vessels, and its secondary outcome concerns contrast volume used. These definitions identify the questions the study was intended to address, but they do not establish which approach had higher or lower enhancement or used more or less contrast.
No numerical results for the primary or secondary outcomes are reported in the registry record. There are no reported group means, standard deviations, estimates of between-group differences, confidence intervals, or p-values. Therefore the direction, magnitude, and precision of the outcome comparisons cannot be evaluated from the registry record. It is not possible to conclude from this record that the dosing approaches were equivalent, different, or ranked in any particular order.
The record reports total enrollment of 139 and describes the study as randomized, single-masked, and parallel-group. Those design features provide context for the intended comparison, but the record does not supply group-specific enrollment, participant flow, analysis populations, or the statistical model. The planned arm descriptions should not be mistaken for observed analysis counts.
General statistical explanation: a non-significant test, if one had been reported, would not by itself prove equivalence; equivalence requires a defined margin and an analysis designed to assess it. Likewise, an estimate without sufficient precision can leave a wide range of plausible effects. Since no test or estimate is reported, neither conclusion is available.
The record does document zero serious and zero other adverse events in the listed group counts, with group-specific numbers at risk. Those counts are limited to the registry's event reporting and do not resolve the absence of outcome analyses or provide a complete safety profile. Overall, this registry record supports description of the trial question and design, but not a statistical judgment about comparative imaging results.
13. Why This Trial Matters Statistically
This trial is statistically interesting because the dosing strategies are based on different definitions of body size. The registry distinguishes total body weight from calculated, measured, and estimated lean body weight, alongside a fixed-dose approach. That makes the study a comparison of measurement strategies as well as a comparison of contrast-dosing rules. The primary imaging outcome and the secondary contrast-volume outcome address related but distinct aspects of those strategies.
The endpoint also illustrates why outcome construction matters. Enhancement is measured in several anatomical regions before and after contrast administration, and the registry describes a summed measurement. A single summary can make a comparison easier to state, but readers need to know how component measurements are combined and how repeated image measurements contribute. Some measurement details are described; a complete analysis definition is not reported in the registry record.
More broadly, a randomized design can be useful for comparing multiple approaches, but its interpretability depends on reporting actual group sizes, outcome summaries, uncertainty, and the analysis plan. In this record, the endpoint definitions and design are available, while numerical outcome analyses are not. That contrast makes clear that a trial's registration can explain what researchers intended to measure without supplying the evidence needed to estimate comparative effects.
The record also lists a planning illustration based on an observed effect and specified assumptions. Such calculations can help readers understand how target effects and design assumptions relate to sample-size planning. They are not a replacement for the observed estimates and their uncertainty, and they should not be treated as observed power. The registry does not report its own sample-size justification or numerical outcome analyses.
For biostatisticians and clinical researchers, the key lesson is to separate design information, outcome definitions, and analyzed results. Each contributes a different part of the evidence. In this case, the first two are described, but the comparative results are not reported in the registry record.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main limitation for interpreting this specific trial is that the registry record does not report numerical results for either listed outcome. Without group-level enhancement summaries or a comparison estimate, the primary imaging question cannot be answered from the record. The secondary contrast-volume outcome is likewise defined but not numerically reported.
Several design and implementation details are absent. The record does not report the randomization procedure, allocation concealment, which parties were masked, or participant flow by group. It gives overall enrollment as 139 but does not report actual group sizes for the primary analysis or the number of participants with usable endpoint measurements. The arm descriptions contain planned group sizes, which should not be treated as observed analysis counts.
The endpoint is described as a summed measurement across operator-defined regions, with measurements made before contrast and after contrast on liver slices. The registry does not fully specify the calculation used to create the sum, the exact handling of the multiple post-contrast measurements, or procedures for assessing measurement consistency. The statistical model and treatment of baseline measurements are also not reported.
The record does not describe a multiplicity plan, missing-data approach, or analysis population. These omissions limit assessment of the credibility and precision of any potential treatment comparison. The registry's adverse-event counts are restricted to the reported categories and group counts; deaths are not reported, and broader safety ascertainment details are absent.
Finally, the registry does not report the trial's sample-size justification or numerical analysis results. The listed planning assumptions are not evidence of the trial's design rationale or observed effect. These limitations concern what can be established from the registry record and do not imply that unreported procedures or analyses were not conducted.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Use of Electrical Impedence to Measure Lean Body Weight as a Determinant of the Dose of Contrast Media for Abdominal CT — NCT02170688.
- Registry record last updated 2015-01-07; status last verified 2014-12.
- Results first posted 2014-12-12.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT02170688 is a completed Phase 4 randomized, single-masked, parallel-group trial sponsored by Duke University. The registry reports enrollment of 139, a start date of 2004-02, and primary completion in 2014-07. The study compares fixed-dose, total-body-weight, calculated lean-body-weight, measured lean-body-weight, and estimated lean-body-weight approaches to contrast dosing for abdominal CT.
The primary outcome is the difference in liver and blood-vessel enhancement over time, measured in Hounsfield units, with baseline and post-dose imaging approximately 1hr after administration. Contrast volume used is listed as a secondary outcome. The registry record does not report numerical results or registered analyses for these outcomes. It lists zero serious and zero other adverse events in the reported group counts; death counts are not reported.